Breeding of Orchardgrass Cultivars with High WSC Content for Hokkaido and Tohoku Regions, Japan

Abstract

Hokkaido’s dairy industry relies heavily on forage self-sufficiency. Improving feed quality remains critical for management efficiency and reducing dependence on imported feed. Although timothy (Phleum pratense L.) is the dominant grass in the region, its productivity is declining owing to weed invasion. Orchardgrass (Dactylis glomerata L.) offers a superior alternative owing to its environmental tolerance and compatibility with legumes; however, its lower sugar content than other grasses can limit livestock intake and silage fermentation. To address this, the Hokkaido Agricultural Research Center (HARC) developed a comprehensive set of high-water-soluble-carbohydrate (WSC) orchardgrass cultivars across all maturity groups—‘Wasejiman’ (early), ‘Esajiman’ (medium), ‘Kitahare’ (late), and ‘Kitajiman’ (very late)—using a recurrent selection strategy. These cultivars achieved a 2–3 percentage-point increase in WSC content and an 8% increase in total digestible nutrient yield without compromising dry matter yield. Feeding trials using ‘Esajiman’ silage demonstrated a 5% increase in dry matter intake and a 4% increase in fat-corrected milk yield in dairy cows. These findings confirm that breeding for high WSC effectively enhances nutritional value, intake, and milk productivity. The widespread adoption of these cultivars should improve the profitability and sustainability of livestock operations in cold-temperate regions of Japan.